Power semiconductor devices are designed to be tolerant of the high currents and voltages that are present in power applications such as power train, motion control, air bag deployment, automotive fuel injector drivers, DC/DC, DC/AC, and AC/DC converters, and other power electronics instruments. Power semiconductor devices, such as insulated gate bipolar junction transistor (IGBT) and field effect transistor (FET) devices, are often used as electronic switches in such applications. IGBT and other power devices are often arranged and packaged in a power electronics module. Multiple modules may be used in circuits to provide phased or alternating current power to inductive loads such as motors or to increase power density.
Multiple aspects of the circuits are designed in an effort to accommodate the currents and noise resulting from inductive loads and/or parasitic inductances during the switching provided by the power semiconductor devices. For example, decoupling capacitors may be incorporated into the circuits to mitigate the effects of noise introduced by parasitic inductances. The decoupling capacitors may decouple portions of the circuit to protect devices from voltage spikes resulting from the parasitic inductances.
Electrical interconnects within power electronics modules present parasitic inductances. For example, wire bonds often introduce inductive noise during switching. In many modules, wire bonds are relied upon to connect terminals of a power semiconductor device to a lead frame. Some wire bonds accordingly handle high currents in many applications. Other wire bonds may also present inductive noise, including those wire bonds used to connect off-chip decoupling capacitors.
These parasitic inductances of such wire bonds may lead to a voltage spike or over-voltage in power electronics modules. Over-voltages may occur in connection with the sudden interruption of current flow to an inductive load despite the decoupling capacitors and other efforts to prevent such over-voltages. These and other over-voltages may destroy the power semiconductor device.
Snubbers are often used to protect the power semiconductor devices. Snubbers attempt to conduct undesirable transient currents around the power semiconductor device. Unfortunately, snubbers typically increase the manufacturing cost of the device and consume space and energy.